This invention relates to solid state cameras and more particularly to such a camera which requires a sealed or vacuum environment.
U.S. Pat. No. 5,393,931 issued Feb. 28, 1995 discloses a camera which employs a circuit board to complete a vacuum seal and yet permit passage of electrical conduits through the board to a charge coupled device (CCD) inside a vacuum chamber. The vacuum chamber also included a molecular sieve which ensured that the requisite level of dryness was present within the chamber. The chamber was necessarily relatively large to accommodate the sieve and, of course, the sieve was not replaceable once the camera was manufactured.
In accordance with the principles of this invention, the molecular sieve is placed in a separate chamber in close proximity to the vacuum tight detector chamber and connected thereto via a small conduit. The sieve chamber functions as a passive pump to remove water vapor from the detector chamber and permits the minimizing of the size of the detector chamber and the placement of the amplifier circuit close to the CCD. The sieve chamber also is vacuum tight and has a removable cover which permits the sieve to be replaced after manufacture.